How this conversion works
Charge is current multiplied by time. One coulomb is one ampere flowing for one second, so one ampere-hour is 3,600 C and one milliampere-hour is 3.6 C.
Since the 2019 SI redefinition, the elementary charge is exactly 1.602176634 × 10⁻¹⁹ C.
Formula: result = value × (base units per source unit) ÷ (base units per target unit)
Where this conversion is used
- Battery capacity in mAh or Ah compared with coulombs.
- Electrochemistry and electroplating calculations (faradays).
- Physics problems counting electrons or charge in coulombs.
Worked example: A 3,000 mAh battery in coulombs
- 1 mAh = 0.001 A × 3,600 s = 3.6 C.
- 3,000 × 3.6 = 10,800 C.
Unit definitions
| Unit | In coulombs | Note |
|---|---|---|
| Coulomb (C) | 1 | 1 ampere for 1 second. |
| Millicoulomb (mC) | 0.001 | |
| Microcoulomb (µC) | 0.000001 | |
| Nanocoulomb (nC) | 1e-9 | |
| Ampere-hour (Ah) | 3,600 | |
| Milliampere-hour (mAh) | 3.6 | |
| Elementary charge (e) | 1.60218e-19 | 1.602176634 × 10⁻¹⁹ C exactly (SI 2019). |
| Faraday (F (charge)) | 96,485.3321233 | Charge of one mole of electrons ≈ 96,485.332 C. |
| Abcoulomb (abC) | 10 | |
| Statcoulomb (statC) | 3.33564e-10 |
Milliampere-hours to coulombs
| Milliampere-hour (mAh) | Coulomb (C) |
|---|---|
| 100 | 360 |
| 500 | 1,800 |
| 1,000 | 3,600 |
| 2,000 | 7,200 |
| 3,000 | 10,800 |
| 5,000 | 18,000 |
Ampere-hours to coulombs
| Ampere-hour (Ah) | Coulomb (C) |
|---|---|
| 1 | 3,600 |
| 2 | 7,200 |
| 10 | 36,000 |
| 50 | 180,000 |
| 100 | 360,000 |
Things to watch for
- mAh measures charge, not energy. To estimate energy in watt-hours, multiply ampere-hours by the battery's nominal voltage.
Precision and sources
Results are calculated from the definitions above and rounded to 12 significant digits; the converter shows up to eight decimal places and the tables four. Reference: BIPM, The International System of Units (SI Brochure), 9th edition (2019).
Frequently asked questions
How do I convert mAh to Wh?
Wh = (mAh ÷ 1,000) × volts. A 3,000 mAh battery at 3.7 V holds about 11.1 Wh. This uses a voltage you supply, so it is not part of this converter.